single-cell-calcium-imaging-for-studying-activation-calcium-ion

Single-Cell Calcium Imaging for Studying the Activation of Calcium Ion Channels

Single cell Ca2+ imaging is essential for the study of Ca2+ channels activated by various stimulations like temperature, voltage, native compound and ...

Beijing University of Chinese Medicine

Activated B cells targeted to autoantigens proliferate and differentiate into antibody-secreting cells. Overproduced autoantibodies will give rise to autoimmune diseases. In this study, we investigated the inhibitory effects of GYF-21, an epoxide 2‑(2‑phenethyl)‑chromone derivative extracted from Chinese agarwood, on the survival, activation, proliferation, and differentiation of B cells for revealing its potential to treat autoimmune diseases related to B cell dysfunction. The results showed that GYF-21 slightly inhibited the survival, activation and proliferation of B cells stimulated by combination of anti-IgM, anti-CD40 and IL-4 while weakly up-regulated differentiation of B cells induced by combination of anti-CD40 and IL-4. In addition, GYF-21 intensively suppressed survival, activation, proliferation, and differentiation of B cells stimulated by B-cell activating factor (BAFF) which plays extremely important roles in autoantibody production and pathogenesis of autoimmune diseases. The mechanism study revealed that GYF-21 slightly down-regulated phosphorylation of NF-κB p65, Akt, STAT3, but up-regulated phosphorylation of Erk1/2 in B cells activated by anti-IgM, anti-CD40, IL-4 or their combinations. However, GYF-21 not only moderately down-regulated phosphorylation of NF-κB p65 and MAPK p38, but also intensively inhibited phosphorylation of Erk1/2 and Akt induced by BAFF. These data suggest the inhibitory effects of GYF-21 on the survival, activation, proliferation, and differentiation of B cells mainly via blocking BAFF activated signaling pathways, and its potential to be developed into therapeutic drug for autoimmune diseases, especially systemic lupus erythematosus (SLE).

GYF-21, an epoxide 2‑(2‑phenethyl)‑chromone derivative, suppresses dysfunction of B cells mainly via inhibiting BAFF activated signaling pathways.

Hematopoietic stem cell transplantation (HSCT) plays an important role in the therapy of hematological malignancies and some nonmalignant diseases. Granulocyte colony-stimulating factor (G-CSF) is generally used to mobilize and collect hematopoietic stem cells from donors and accelerate neutrophil recovery in transplantation recipients. However, less attention has been paid to the fact that G-CSF administration might result in thrombocytopenia and enhance bleeding risk in HSCT. In this study, we investigated the effects of G-CSF on platelet counts in healthy mice and mice that received bone marrow transplantation. It was observed that G-CSF administration induced thrombocytopenia in healthy mice and aggravated thrombocytopenia in mice that received bone marrow transplantation. Furthermore, we analyzed the regulatory effects of G-CSF on the differentiation of hematopoietic progenitors and megakaryocytes, and activation of platelets and endothelial cells. The results reveal that G-CSF administration causes thrombocytopenia mainly by inhibiting the differentiation of common myeloid progenitors and megakaryotic erythroid progenitors into megakaryocytes and platelet formation but not through enhancing activation of platelets or endothelial cells and following platelet consumption. Collectively, G-CSF administration can result in thrombocytopenia in hematopoietic stem cell donors and exacerbate existing thrombocytopenia in transplantation recipients. More attention should be paid to bleeding risk of G-CSF administration in HSCT, especially autologous HSCT.

G-CSF administration results in thrombocytopenia by inhibiting the differentiation of hematopoietic progenitors into megakaryocytes.

Activated platelets release adenosine trisphosphate (ATP) and bioluminescence analysis of ATP release is usually used to monitor activation of platelets induced by various stimulants. However, bioluminescence analysis of ATP possesses poor linearity, the signal is quickly attenuated, and the accuracy of ATP release from platelets is hard to determine accurately enough to be used in a high throughput screening of platelet inhibitors. The present study was designed to optimize bioluminescence analysis of ATP released by platelets and expand its application in high throughput screening of platelet inhibitors. The results showed that accuracy of ATP analysis was significantly improved by adding coenzyme A (CoA) and signal attenuation of ATP analysis was greatly postponed by adding bovine serum albumin (BSA) both in Hank's balanced salt solution (HBSS) and Tyrode's buffer. Furthermore, ATP release of activated platelets and inhibitory effects of Ly294002 and Staurosporine on platelet activation were accurately determined by our optimized bioluminescence analysis of ATP. Thus, we have successfully constructed an optimized bioluminescence analysis of ATP which can be used in high throughput screening of platelet inhibitors.

Optimized bioluminescence analysis of adenosine triphosphate (ATP) released by platelets and its application in the high throughput screening of platelet inhibitors.

Superoxide plays a key role in normal immune function and inflammatory diseases. In order to evaluate normal immune function or screen inhibitors of superoxide production for treating inflammatory diseases, it is very important to detect superoxide with good accuracy, sensitivity, and flexibility. In present study, we investigated three analysis methods of superoxide, colorimetric assay by WST-8, fluorescence assay by dihydroethidium and chemiluminescence assay by lucigenin, compared their precisions, specificities, sensitivities and time curve characteristics in superoxide analysis, and then validate their values in the screening of anti-inflammatory compounds. The results reveal that three analysis methods of superoxide all have good precisions and high specificities but have different sensitivities and time curve characteristics, which suggest their different applications. In addition, they can all be used in the screening of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors and anti-inflammatory compounds.

Comparison of three analytical methods for superoxide produced by activated immune cells.

Nonalcoholic fatty liver disease (NAFLD) has become one of the most prominent causes of chronic liver diseases and malignancies. However, few therapy has been approved. Radix Bupleuri (RB) is the most frequently used herbal medicine for the treatment of liver diseases. In the current study, we aim to systemically evaluate the therapeutic effects of saikosaponin A (SSa) and saikosaponin D (SSd), the major bioactive monomers in RB, against NAFLD and to investigate the underlying mechanisms. Our results demonstrated that both SSa and SSd improved diet-induced NAFLD. Integrative lipidomic and transcriptomic analysis revealed that SSa and SSd modulated glycerolipid metabolism by regulating related genes, like  and . SSd profoundly suppressed the fatty acid biosynthesis by downregulating  and  expression and promoted fatty acid degradation by inducing  and  expression. Bioinformatic analysis further predicted the implication of master transcription factors, including peroxisome proliferator-activated receptor alpha (PPAR), in the protective effects of SSa and SSd. These results were further confirmed  in mouse primary hepatocytes. In summary, our study uncoded the complicated mechanisms underlying the promising anti-steatosis activities of saikosaponins (SSs), and provided critical evidence inspiring the discovery of innovative therapies based on SSa and SSd for the treatment of NAFLD and related complications.

Yunqian Li

School of Life Science

Beijing University of Chinese Medicine

Single-Cell Calcium Imaging for Studying the Activation of Calcium Ion Channels